JP2005166354A - Ceramic heater - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve a uniform heating property on a heating face of a ceramic base body and elongate its life at impression of heat cycles, for a heater with its ceramic base body fitted with through-holes. <P>SOLUTION: The ceramic heater, made of ceramics, with a heating face, is provided with the base body divided into three or more zones 3C, 3F, a resistive heating element set in correspondence with each zone, and a terminal 5C electrically connected with each resistive heating element. The base body has at least three though-holes formed, with a distance n between the terminal 5C and a wall face of the through-hole of 8 mm or more. The resistive heating element 15 crosses a straight line 16 connecting the center 5a of the terminal and that 4a of the through-hole. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a ceramic heater suitable for semiconductor heating and the like.

  In a semiconductor manufacturing apparatus, a ceramic heater for heating a wafer is employed in manufacturing a semiconductor thin film from a raw material gas such as silane gas by thermal CVD or the like. In such a ceramic heater, it is essential to highly uniform the temperature of the heating surface and the semiconductor wafer placed thereon.

  In such a ceramic heater, various methods for making the temperature of the heating surface of the heater uniform are known. For example, a so-called two-zone heater is one such technique. The two-zone heater embeds an inner peripheral resistance heating element and an outer resistance heating element made of a refractory metal in a ceramic substrate, and forms a separate current introduction terminal for each resistance heating element. By independently applying a voltage to the body, heat generation from the inner peripheral resistance heating element and the outer peripheral resistance heating element is independently controlled.

In Patent Document 1, nine zones of resistance heating elements are embedded in a ceramic substrate, and through holes are formed in the ceramic substrate.
JP 2001-52843 A

  When a ceramic heater is used as a susceptor for installing a semiconductor wafer, a lift pin hole for inserting a lift pin for supporting the semiconductor wafer, a gas supply hole for supplying backside gas, a thermocouple, Various holes may be provided such as a thermocouple insertion hole for inserting a thermocouple. When holes, particularly through holes, are provided in the ceramic substrate, these holes become structural defect portions of the ceramic substrate.

  Here, in the ceramic heater of Patent Document 1, the terminals of the second and third zones from the inside are arranged in a portion very close to the through hole, and the periphery of the terminal and the through hole becomes a cold spot, so that the heat uniformity is good. It turned out to be reduced. In addition, since the temperature difference between the periphery of the terminal and the through hole and other regions becomes large, the repeated use of the heater tends to break the ceramic substrate, resulting in a short life.

  An object of the present invention is to improve the thermal uniformity on the heating surface of the substrate in a heater in which through holes are provided in the ceramic substrate, and to extend the life of the ceramic substrate when a thermal cycle is applied.

The present invention is made of ceramics, has a heating surface, is divided into three or more zones, a resistance heating element installed corresponding to each zone, and each resistance heating element electrically A ceramic heater with connected terminals,
Three or more through holes are formed in the base, the distance between the terminal and the wall surface of the through hole is 8 mm or more, and at least one of the resistance heating elements has a straight line connecting the center of the terminal and the center of the through hole. It is characterized by crossing.

  According to the present invention, the distance between the terminal and the wall surface of the through hole is 8 mm or more, and the resistance heating element is designed to cross a straight line connecting the center of the terminal and the center of the through hole. As a result, cool spots and hot spots on the substrate surface can be suppressed to improve the thermal uniformity, and the life of the ceramic substrate when a heat cycle is applied can be extended.

Hereinafter, the present invention will be described in more detail with reference to the drawings as appropriate.
FIG. 1 is a plan view showing an installation pattern of zones, through-holes and terminals in a ceramic heater 1A according to an embodiment of the present invention. FIG. 2 shows insertion of zones, through-holes, terminals and thermocouples in a ceramic heater 1B. It is a top view which shows the installation pattern of a hole. FIG. 3 is a cross-sectional view schematically showing an installation pattern of resistance heating elements and terminals in the heater of FIG. 1 or FIG.

  In the example of FIGS. 1 and 2, the base 2 has a substantially disk shape. The base body 2 is provided with a plurality of heating element burying zones, for example, six heating element burying zones 3A, 3B, 3C, 3D, 3E, and 3F. In this example, the zone 3A is in the center of the base 2 and has a substantially circular shape. Zone 3B is ring-shaped. Zones 3C, 3D, 3E, and 3F are formed so as to divide the ring into four on the outside of zone 3B.

  In each zone, resistance heating elements capable of controlling the heat generation amount independently of each other are embedded. Each heating element in each zone 3A, 3B, 3C, 3D, 3E, 3F is connected to each terminal 5A, 5B, 5C, 5D, 5E, 5F, respectively. Each of the terminals 5A to 5F is connected to a power supply member 10 outside the base as shown in FIG. 3, and this is connected to an external power source via a power cable and a rod (not shown). A tubular support member 11 is attached to the back surface 2 b of the base 2, and the terminal, the power supply member 10, the power cable, and the rod face the space 12 in the support member 11. The joining method of the base body 2 and the support member 11 is not particularly limited, and can be joined by, for example, brazing material or bolting, or can be solid-phase joined as described in JP-A-8-73280. Further, the heater and the support member can be sealed and bonded using a seal member such as an O-ring or a metal packing. The support member 11 is attached to the chamber 13. Reference numeral 4 denotes a through hole for inserting a lift pin and a backside gas supply hole.

  Here, according to the present invention, the distance n between the terminal and the through hole is set to 8 mm or more, and the resistance heating element is passed between the center of the terminal and the center of the through hole. For example, as shown in FIG. 4, the distance n between the outer peripheral surface of the terminal 5C and the inner wall surface of the through hole 4 is 8 mm or more, and a straight line connecting the center 5a of the terminal 5C and the center 4a of the through hole 4 16 is designed such that the resistance heating element 15 traverses. Hereinafter, this effect will be described.

  In the present invention, in order to improve the thermal uniformity of the heating surface of the substrate, the number of resistance heating elements to be controlled is increased to three or more, and the heat generation from each zone is controlled separately, thereby finely controlling the in-plane. Temperature distribution can be controlled. Depending on the temperature distribution at the time of temperature rise, thermal stress may occur in the heater plate and breakage may occur, but by controlling the temperature independently for each zone, the generated thermal stress is reduced and damage is avoided. As a result, it is possible to improve the in-plane distribution, and it is possible to reduce the damage to the heater.

  However, when the number of zones is increased, the number of terminals also increases with the number of resistance heating elements. Here, if it demonstrates with reference to FIG. 4, since the terminal 5C and the through-hole 4 do not generate | occur | produce heat | fever, the site | part area which does not generate | occur | produce will become large and can become a cool spot. However, if the distance n between the terminal and the through hole is small, an effective resistance heating element cannot be laid out between them. Therefore, it has been found that it is necessary to secure an insulation distance, and it is essential to secure 8 mm or more as the distance n. If this is less than 8 mm, a leakage current between ceramic materials is generated, and a hot spot is formed instead of a cool spot. The formation of cool spots or hot spots not only deteriorates the temperature distribution soaking, but also causes thermal stress and damages the heater, so it needs to be improved.

  Here, the occurrence of hot spots can be prevented by setting n to 8 mm or more. At the same time, it has been found that by passing the resistance heating element 15 between the terminal and the through hole, the cold spot can also be erased, thereby improving the thermal uniformity and preventing the substrate from being damaged when the heat cycle is applied. When such a resistance heating element does not exist, as shown in FIG. 5, since there is no heat source in the terminal 5C and the through hole 4 and the periphery thereof, a cool spot is likely to occur.

  Since design becomes difficult if the distance n between the terminal and the through hole is too large, it is preferably 290 mm or less.

  Each zone of the ceramic plate in which each resistance heating element is embedded usually has one hole for a temperature measuring element such as a thermocouple (not shown in FIG. 1). However, with this method, the temperature control thermocouples of the heaters arranged in these holes interfere with each other due to the location of the thermocouple holes and the influence of the chamber environment in which the heaters are used. As a result, there is a problem that the temperature of each zone cannot be controlled appropriately.

  Therefore, in a preferred embodiment, two or more temperature measurement holes can be provided for each zone. This makes it possible to select a hole position that can reduce the temperature interference between the zones in accordance with the chamber environment in which the heater is used. By disposing the temperature measuring element in the selected hole, it is possible to suppress the deterioration of the operation of the temperature measuring element due to the temperature interference between the zones, and to improve the heat uniformity of the heating surface.

  The ceramic constituting the substrate is not particularly limited. However, the base material may be a known ceramic material such as nitride ceramics such as aluminum nitride, silicon nitride, boron nitride and sialon, and alumina-silicon carbide composite material. In order to impart high corrosion resistance to corrosive gases such as halogen-based gases, aluminum nitride and alumina are particularly preferable.

  When a tubular support member is used, the material of the support member is preferably aluminum nitride, silicon nitride, alumina, or the like. A metal containing aluminum can also be selected as appropriate.

  Although the shape of a base | substrate is not specifically limited, A disk shape is preferable. The shape of the heating surface may be a pocket shape, an embossed shape, or a groove shape.

  Although the manufacturing method of a base | substrate is not limited, The hot press manufacturing method and the hot isostatic press manufacturing method are preferable.

  The material of the resistance heating element is preferably a refractory metal such as tantalum, tungsten, molybdenum, platinum, rhenium, hafnium nickel, and alloys thereof. In particular, when the ceramic substrate is made of aluminum nitride, molybdenum and a molybdenum alloy are preferable. In addition to the refractory metal, a conductive material such as carbon, TiN, or TiC can also be used. The shape of the resistance heating element may be a coil shape, a ribbon shape, a mesh shape, a plate shape, a film shape, or the like.

  The form and material of the terminal electrically connected to the resistance heating element are not limited, but may be the material for the resistance heating element described above.

  The application of the ceramic heater of the present invention is not particularly limited, but is preferably used for a semiconductor manufacturing apparatus. This semiconductor manufacturing apparatus means an apparatus used in a wide range of semiconductor manufacturing processes where there is a concern about metal contamination of semiconductors. This includes an etching apparatus, a cleaning apparatus, and an inspection apparatus in addition to the film forming apparatus.

  The form of each power supply member is not limited, and examples thereof include a rod shape, a wire shape, and a composite of a rod and a wire. The material of the power supply member is not limited. Since these are isolated from the atmosphere in the chamber by a tubular support member and are not easily corroded, the material is preferably metal, and nickel is particularly preferable.

  A high-frequency electrode element and an electrostatic chuck element can also be embedded in the substrate.

  The terminal may be disposed on the ceramic substrate after being electrically connected to the resistance heating element in advance. Further, after the resistance heating element is disposed on the base, the terminal may be electrically connected to the resistance heating element. For electrical connection between the terminal and the resistance heating element, screws, caulking, fitting, brazing, welding, eutectic and the like can be applied.

  The material of the power supply member from the outside of the ceramic substrate is preferably a metal, and particularly preferably nickel. For the electrical connection between the terminal member and the power supply member, screws, caulking, fitting, brazing, welding, eutectic and the like can be applied.

  The layout or pattern of each arrangement zone of each resistance heating element is not limited. For example, a plurality of ring-shaped zones can be arranged concentrically. Further, one ring-shaped zone can be divided into a plurality of arc-shaped zones like the zones 3C, 3D, 3E, and 3F in FIGS. The opening angle of the arc at this time is not particularly limited.

(Example 1)
A heater 1A shown in FIGS. 1 and 2 was produced. The substrate 2 was an aluminum nitride sintered body, the substrate had a diameter φ of 340 mm, and a thickness of 14 mm. Inside the substrate 2, a wound body of molybdenum wire was embedded as a resistance heating element in accordance with each zone. Each terminal was a molybdenum cylindrical terminal, and a molybdenum wire was attached by caulking. The obtained ceramic substrate was processed to expose the surface of the molybdenum terminal, and the nickel cylindrical component 10 was brazed as a power supply member.
The support member 11 was formed of an aluminum nitride sintered body. The support member 11 was solid-phase bonded to the back surface 2 b of the base 2. A nickel rod was inserted into the inner space 12 of the support member 11 and electrically connected to each member 10.

  In the ceramic base, three through holes 4 for lift pin holes were provided at equal intervals of 280 mm from the center of the base 2. The diameter of the through hole was 4 mm. One thermocouple hole was provided for each zone. The distance n between each terminal and each side surface of each through hole was 8 mm or more as shown in FIG. A resistance heating element is disposed so as to cross a straight line 16 connecting the center of each terminal and the center of each through hole. The resistance heating element disposed so as to cross the straight line connecting the terminal and the center of each through hole may be a resistance heating element connected to a terminal other than the terminal.

(Example 2)
In the same manner as in Example 1, a heater 1B having a pattern as shown in FIG. However, two thermocouple holes were provided for each zone, and after installing the heater in the chamber, the optimum hole with less temperature interference was selected for each zone, and a thermocouple was installed. .

(Comparative Example 1)
A heater was produced in the same manner as in Example 1. However, as shown in FIG. 5, the distance n between the terminal 5C and the through-hole 4 was set to 7 mm so that the resistance heating element did not pass through the straight line 16.

(Comparative Example 2)
A heater was produced in the same manner as in Example 1. However, as shown in FIG. 4, the resistance heating element was passed between the terminal and the through hole, and the distance n between the terminal outer peripheral surface and the wall surface of the through hole 4 was 7 mm.

  Power was supplied to each heater, the temperature was measured with a thermocouple disposed in the thermocouple hole, and the power source was feedback controlled using this temperature. Thus, the temperature was controlled at 700 ° C., and the temperature distribution on the heater plate surface (in-plane temperature difference ΔT) was confirmed. Moreover, the heat cycle test of 200 degreeC and 700 degreeC was implemented, and the cycle number which resulted in heater failure was confirmed. The results are shown in Table 1.

  In Examples 1 and 2 of the present invention, the temperature distribution ΔT was small, and no damage was observed until after 100 cycles. In the second embodiment, it is possible to perform control such that the temperature distribution ΔT is further reduced. In Comparative Example 1, no damage was observed until after 100 cycles, but the temperature distribution ΔT increased to 12 ° C. This is because a cool spot is generated around the terminal and the through hole. In Comparative Example 2, the temperature distribution reached 36 ° C., and the substrate was damaged after 82 cycles. This is because a hot spot is generated by a leakage current because a resistance heating element is passed between the terminal and the through hole while reducing n.

In heater 1A which concerns on one Embodiment of this invention, it is a figure which shows the planar pattern of zones 3A-3F, the through-hole 4, and the terminals 5A-5F. In heater 1B which concerns on one Embodiment of this invention, it is a figure which shows the planar pattern of the zones 3A-3F, the through-hole 4, the terminals 5A-5F, and the hole 8 for temperature measuring elements. It is sectional drawing which shows schematically the positional relationship of the resistance heating element, the terminal, and the supporting member 11 in heater 1A (1B). It is a figure which shows the planar positional relationship of the through-hole 4, the terminal 5C, and the resistance heating element 15 in this invention. It is a figure which shows the planar positional relationship of the through-hole 4 and the terminal 5C in a comparative example.

Explanation of symbols

  1A, 1B Ceramic heater 2 Ceramic substrate 2a Heating surface 2b Back surface 3A, 3B, 3C, 3D, 3E, 3F Zone 4 Through hole 4a Center of through hole 4 5A, 5B, 5C, 5D, 5E, 5F Terminal 5a Terminal center DESCRIPTION OF SYMBOLS 10 Power supply member 11 Support member 16 Straight line which connects terminal center and through-hole center n Distance between terminal and through-hole wall surface

Claims (6)

A substrate made of ceramics, having a heating surface, divided into three or more zones, a resistance heating element installed corresponding to each zone, and electrically connected to each of the resistance heating elements A ceramic heater equipped with a terminal,
Three or more through holes are formed in the base, the distance between the terminal and the wall surface of the through hole is 8 mm or more, and the resistance heating element includes a center of the terminal and a center of the through hole. A ceramic heater characterized by crossing a straight line connecting the two.   The ceramic heater according to claim 1, wherein the resistance heating element is embedded in the substrate.   The ceramic heater according to claim 1 or 2, wherein the substrate is made of aluminum nitride.   The ceramic heater according to any one of claims 1 to 3, wherein the resistance heating element is made of a metal containing tungsten or molybdenum.   The tubular support member is attached to the back side of the base, and the terminal is disposed on the inner side of the support member. The ceramic heater described.   The ceramic heater according to any one of claims 1 to 5, wherein each of the zones is provided with two or more mounting holes for temperature measuring elements.

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